(AP) — U.S. Census Bureau computer servers were exploited last year during a cybersecurity attack, but it didn't involve the 2020 census.

A watchdog report released Wednesday says the hackers’ attempts to keep access to the system were unsuccessful.

The attack took place in January 2020 on the bureau’s remote access servers.

According to the Office of Inspector General, the Census Bureau missed opportunities to limit its vulnerability to the attack and didn’t discover and report the attack in a timely manner.

In a written response, acting Census Bureau director Ron Jarmin reiterated that none of the systems used for the 2020 census were compromised.